Many computer systems use magnetic disk drives for mass storage of information. Magnetic disk drives typically include one or more sliders having a read head and a write head. An actuator/suspension arm holds the slider above the surface of a magnetic disk. When the disk rotates, an air flow generated by the rotation of the disk causes an air bearing surface (ABS) side of the slider to fly at a particular height above the disk. As the slider flies on the air bearing, a voice coil motor (VCM) moves the actuator/suspension arm to position the read/write head over selected tracks of the disk. The read/write head may then read data from or write data to the tracks of the disk.
A typical write head includes a main write pole and a return pole. The main write pole has a yoke portion and a pole tip portion. The pole tip extends from the ABS of the recording head to the yoke of the write pole. The point where the pole tip meets the yoke is referred to as the flare point. The point where the yoke begins has a trapezoidal shape that flares outwardly from the pole tip. The yoke of the main write pole then connects to the return pole through a back gap. A coil wraps around the yoke or the back gap to provide the magnetic flux used for the write operation. The width of the pole tip controls the track width that is written by the recording head, so the width of the pole tip is preferably small (i.e., less than 100 nanometers).
Write heads and other components of the slider are typically produced using thin-film deposition and patterning techniques. Material layers which make up a write head for a slider are typically formed by depositing full film materials of the main write pole layers on a non-magnetic layer (e.g., alumina), depositing and patterning a masking layer over the main write pole layers to form a mask structure, etching the exposed portion of the main write pole layers around the mask structure to define a pole tip and a flare point of the write pole, and then removing the mask structure. A trailing shield or a wrap around shield may then be formed around the pole tip. A shield is formed to prevent the main write pole from inadvertently writing to neighboring tracks.
After the read/write heads are formed, the sliders are cut from the wafer into individual sliders, or rows of sliders. The surfaces of the sliders that are exposed when the wafers are cut will eventually form the air bearing surface (ABS) of the slider.
A lapping process is used to form the ABS of a slider, and more particularly, the ABS of the write head. To monitor progress of the lapping process, electronic lapping guides (ELG's) may be fabricated proximate to the write pole. Typically, the ELG's in the write head are fabricated by sharing a number of the same steps as with the write pole, which allows features on the ELG (e.g., a front edge) to accurately correlate with features of the main write pole (e.g., a flare point of the yoke). Lapping removes material from the ABS surface of the slider. During the lapping process, the ELG's provide an electrical signal to a test system that indicates information about the current lapping depth. In some ELG's, the electrical signal indicates an abrupt change in resistance when the front edge surface of the ELG is lapped away. This allows the test system operator to determine a distance between the current lapping depth and the flare point of the yoke. This distance is an important design parameter of the write head and therefore, accurately determining the flare point from the current lapping depth during the lapping process is part of the fabrication process. However, during the fabrication process, not all of the steps of the process are shared between the ELG's and the write pole. Thus, during some steps, a mask structure may be applied to cover the main write pole and expose the ELG's. Materials may then be deposited on the ELG's and not on the main write pole (or the opposite). Problems arise however when the mask structure is subsequently removed from around the main write pole tips, as the pole tips are very thin, fragile, and may be easily broken. Further, some shared fabrication processes for the ELG's and the main write pole may adversely impact the final performance of the ELG's more than the write pole, such as eroding features on the ELG's to render the ELG's less accurate for their intended purpose. Therefore, an ongoing need exists for improving the fabrication process of write heads that include ELG's.